The United Left Alliance - which is campaigning for a No vote in the fiscal treaty referendum - has severely criticised the pro-treaty side, saying they cannot be trusted.

Socialist MEP Paul Murphy told reporters this afternoon that over 100,000 jobs had been lost since the 2009 Lisbon II referendum.

He said Fine Gael had then campaigned on the platform that a vote for Europe would be a vote for jobs

The MEP was speaking outside Fine Gael Headquarters in Dublin city centre.

He said it was clear austerity was not working and said people will get their chance to register that fact on 31 May.

The Taoiseach earlier claimed the fiscal treaty referendum vote was more important than a general election because its impact would last "a very long time".

Speaking at the Business for Ireland’s launch of its Yes vote campaign, Enda Kenny said there were three reasons to vote in favour of the treaty on 31 May.

He said it would continue investor confidence in Ireland, would ensure access to the ESM, and would enshrine “good housekeeping” budgetary rules in legislation.

In the Dáil, Mr Kenny later accused Sinn Féin of leading the electorate into "the darkness of confusion" in its stance of the treaty.

He told Gerry Adams that he was the leader of the No campaign, but said he did not think his heart was in it because he saw the impact of the lack of investment in other countries.

Mr Adams had described the Taoiseach as the "poster boy for austerity".

He accused Mr Kenny of handing fiscal sovereignty over to "European central authority" despite having said he wanted to be the Taoiseach to retrieve sovereignty.

Earlier, the Minister for Jobs, Enterprise and Innovation said borrowing costs for Ireland in the open market would rise if the fiscal treaty was rejected.

Richard Bruton said people were mistaken if they believed a No vote would mean no more austerity and a rejection would mean tougher budgets would lie ahead.

He said it was vital that Ireland has access to ESM funds.